This invention relates to a remotely located evaporator assembly for a truck refrigeration system and specifically to construction of an outer covering for the evaporator.
Delivery trucks and trailers transporting temperature sensitive cargo include specially designed climate control systems. Typically, truck climate control systems such as refrigeration systems include a motor and a compressor mounted outside of a cargo area. Refrigerant flows from the compressor into the cargo area to at least one remotely located evaporator unit. The refrigerant flows through an evaporator coil in the evaporator and back to the compressor. Cooling fans mounted within the evaporator blow air across the evaporator coils such that the air is cooled and expelled into the cargo area.
The evaporators mounted within the cargo area are typically composed of a support housing mounted to an interior surface of the cargo area. The evaporator coils and the cooling fans are mounted to the support housing. Refrigerant lines extend into the cargo area from the compressor to provide refrigerant to the evaporators. An outer skin conceals and protects the cooling fans and the evaporator coils. Typically, the outer skin is constructed of aluminum and is secured to the support housing by fasteners. The evaporator includes a drain pan and drain hose to collect and expel condensation that drips from the evaporator coils during normal operation or during a defrost cycle. Insulation is disposed along the inside of the aluminum outer covering to prevent a build up of condensation on the exterior surfaces of the evaporator that may than drip into the cargo area.
The size and shape of the evaporator is dependent on the type of application and the configuration of the delivery truck or trailer. The evaporator may also be constructed as a single or dual discharge. A single discharge evaporator blows air into the compartment from one side, whereas a dual discharge blows cooling air from two sides and includes two evaporator coils. Different sizes and shapes of evaporators require different outer coverings and therefore require fabrication of specific outer coverings for each size and shape of evaporator. Further, the use of aluminum for fabrication of the outer coverings affects the entire design of the evaporator by requiring the use of specific fasteners and support housing configurations, to compensate for the build up of condensation along the outside of the evaporator unit. Further, the plastic outer covering is lighter than an aluminum skin such that the entire evaporator assembly can be fabricated from lighter materials.
For these reasons it is desirable to design an outer covering for remotely mounted evaporators that includes common components, and incorporates separate components to simplify assembly, and reduce the weight.
An embodiment of this invention is an evaporator assembly including a plastic outer covering including integrally formed features to reduce the total number of parts in each evaporator assembly.
The evaporator assembly includes a support housing for mounting to an internal compartment of a delivery truck or trailer. At least one evaporator coil mounts to the support housing along with at least one cooling fan. The evaporator assembly includes a plastic outer skin that incorporates a drain pan to collect condensation and moisture dripping from the evaporator coils during the defrost cycle. The plastic outer covering includes thermal properties that eliminate the need for separate insulation required when using prior art aluminum coverings.
The plastic outer covering is formed with a profile that includes a drain pan section and a planer section. The drain pan section is positioned under the evaporator coils and the planer section is positioned under the cooling fans of the evaporator. The profile includes a hinge that cooperates with the support housing to secure the outer covering at the drain pan section. Fasteners are used to secure the planer section to the support housing. The hinge and fastener configuration allows the outer covering to be swung downward from the evaporator for maintenance and repair without being completely removed.
The plastic outer covering is formed by a plastic extrusion process known as poltrusion. A common tool including the profile of the drain pan and the planer section is used to form long sections that are then cut into the required lengths for each size of evaporator. End caps are attached by an industrial adhesive to the outer covering to form the sides of the drain pan section. One of the end caps includes an integrally formed drain tube to provide for draining of the drain pan.
The profile formed from the poltrusion process is configured for use with a single discharge evaporator as one piece. Dual discharge assemblies require two drain pan sections because of the additional evaporator coil. The additional drain pan section is formed with a common tool by blocking the planer section and forming a length of drain pane sections that is cut to the required lengths.
The plastic outer covering reduces the overall weight of the evaporator unit by replacing multiple features with a single part, and because of the reduced weight of the plastic outer covering and the integral hinge features, a lighter support housing can be used.
The plastic outer covering of this invention simplifies assembly by providing a common profile easily cut into required lengths and by eliminating multiple parts while reducing overall evaporator assembly weight.